This document provides instructions for using an online sample weight calculator to determine the optimal sample weights for isotope analysis. Users enter the percentage of nitrogen and carbon in their material, and the calculator returns results for the smallest and optimal sample weights within limits of 75mg total weight and 12mg of carbon. Sample weights should be optimized to target 20 micrograms of nitrogen while not exceeding 100 micrograms.

1. SAMPLE WEIGHT CALCULATOR
To calculate your optimal sample weights, enter %N and %C values for your sample material in
the blue cells. Calculated results are shown in the green cells. See table for examples of %N and
%C values for various materials. Samples must not exceed either 75mg total weight or 12mg of
carbon. Enriched sample weights should be optimized for 20 ug N, with a maximum of 100
ug N (i.e. use the "Smallest sample weight" to "Optimal sample weight" as your target range).

7. Source : http://stableisotopefacility.ucdavis.edu/sample-weight-calculator.html
(Accessed 26 August 2015)